The arrival of Radamel Falcao at Old Trafford, on loan from Monaco, sparked Welbeck's departure from his boyhood club on a frantic transfer deadline day at the start of September.

Speaking for the first time about the player's sale, on Thursday 11 September, Van Gaal provided a damning assessment of Welbeck, claiming the player had failed to take his chances in his three full seasons in the first team and was not of the standard required at the club.

The decision to sell the 23-year-old has divided opinion among United fans but Redknapp, whose QPR side travel to Old Trafford on Sunday 14 September, believes Van Gaal's record in European football justifies any decision he chooses to make.

"I think they decided if he's going to bring Falcao in and the lads they brought that Welbeck's not going to play and Arsenal have bought a very good player," Redknapp told a press conference.

"But that is the decision of the manager of Manchester United. He's got more decisions right over the years than he has got wrong and that's why he's managed at the top level for so long.

"So who can argue with him?"

Following a summer transfer window that saw 16 players leave the club – either on loan or on permanent deals – and six arrive, Van Gaal now boasts a fearsome attack consisting of Falcao, Robin van Persie and Wayne Rooney with 18-year-old James Wilson also in the Dutchman's thinking.

Speaking to the press, Van Gaal suggested Welbeck's record could not justify a place in his first-team plans.

"When you ask me about Welbeck, he has been here since he is nine, and he spent three years here after being at Sunderland," Van Gaal said. "But he doesn't have the record of Van Persie or Rooney. That's why we let him go – because of Falcao and also the youngsters we have to come in."

Falcao, Daley Blind, Luke Shaw and Marcos Rojo are all expected to make their full United debuts against QPR.